Series connected heater element for multiple electron gun subassembly



Aug. 6, 1968 A. T. KURYL. 3,396,298

SERIES CONNECTED HEATER ELEM T FOR MULTIPLE ELECTRON GUN SUBASSEMBLYFiled Nov. 1. 1966 IN VENT OR.

AAA/v I KURYM W3 7 /z57 BY a/wzjfiw/ F 5 ATTORNZY United States Patent3,396,298 SERIES CONNECTED HEATER ELEMENT FOR MULTIPLE ELECTRON GUNSUBASSEMBLY Alan T. Kuryla, Geneva, N.Y., assignor to Sylvania ElectricProducts Inc., a corporation of Delaware Filed Nov. 1, 1966, Ser. No.591,166 Claims. (Cl. 31370) ABSTRACT OF THE DISCLOSURE A seriesconnection of the heater elements of a threeelectron gun subassembly isprovided by preforming a heater element connecting strap having threeelongated protuberances, each defining a removable area. The connectingstrap is secured to insulating support rods of the gun assembly so thateach protuberance is supported in a fixed spatial relation to one of thecathode elements to permit the connection of the respective heaterelements across the protuberance such that a series connection iscompleted when the removable area of each protuberance is cut out.

This invention relates generally to electron guns and more particularlyto improved means for providing a series connection of the heaterelements in tubes having multiple electron guns. Although having generalapplication, the invention finds particular utility in color picturetubes of the three-gun type.

In multiple electron gun cathode ray tubes, the heater current issupplied to the tube by way of the two stem leads which are in turnconnected to the heater elements of the respective electron guns.According to presently accepted practice, a number of straps are mountedon insulating support rods within the tube and each strap provides aconnection between the ends of heater elements in adjacent electron gunsor between one end of a heater element and an input stem lead. Becauseof the number of straps involved, the mounting operation is relativelytime consuming and great care must be exercised in the mounting of thestraps to assure proper alignment of the straps with the location of theends of the heater elements. If a strap is improperly mounted, theheater element connected thereto may be distorted and thereby affect theoperating characteristics of its associated electron gun. It it alsopossible that an improper mounting may result in a shorting of theheater element. These difliculties are particularly troublesome in colortelevision picture tubes where the failure of any one electron guneffectively renders the tube inoperative.

Accordingly, it is an object of the present invention to provide asimplified, more reliable and economical heater element mountingstructure for multiple electron gun cathode ray tubes.

The foregoing and other objects and advantages are achieved in oneaspect of the invention which utilizes a single preformed connectingstrap which can be positively placed in and fastened to the insulatingsupport rods of the electron gun structure. After the strap is fastenedin place, such as by Welding, voids are cut in the strap atpredetermined positions and the ends of the respective heater elementsare suitably connected across the voids, thereby effecting the desiredseries connection of the heater elements.

For a better understanding of the present invention, together with otherand further objects, advantages and capabilities thereof, reference ismade to the following disclosure and appended claims in connection withthe accompanying drawings, in which:

FIG. 1 is a partial perspective view of -a three electron gun structureembodying the invention;

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FIGS. 2 and 3 are end elevation views of alternate embodiments of theinvention for three electron gun structures;

FIG. 4 is a partial side view of a preformed heater element connectingstraps according to the invention;

FIG. 5 is a partial perspective view of an alternate embodiment of apreformed heater element connecting strap according to the invention;and

FIG. 6 is a partial end view of an alternate configuration of apreformed heater element connecting strap according to the invention.

For simplicity and ease of understanding, the invention will bedescribed in connection with a three-gun structure, such as used in acolor picture tube. However, it will be apparent that the disclosedconcept is applicable to any multiple electron gun structure.

Referring to FIG. 1, there is shown the envelope 11 of a tube withinwhich are contained three insulating support rods 13, 14, and 15.Mounted in the envelope 11 are cylindrical cathode elements 17, 18, and19 within each of which is contained a respective heater element, onlythe ends of which are shown. The cylindrical cathode elements areconnected to the insulating support rods 13, 14, and 15 by suitablecathode mounting straps (not shown). The ends of the heater elements aresupported by four connecting straps 23, 24, 25, and 26, which are, inturn, connected to the support rods 13, 14, and 15 by mounting posts 29,30, 31, and 32, respectively. Connecting members 33 and 35 provideconnections between straps 26 and 23, respectively, and the heaterelement stem leads (not shown). While the connecting straps 23-26 appearas separate elements in the completed structure, they are derived from asingle preformed strap to be later described.

FIG. 2 shows the manner in which the invention provides a supportingseries connection for the heater ele ments '41, 42 and 43 of cathodes45, 46, and 47, respectively, in a three-electron gun structure. Apreformed connecting strap 49 having three elongated protuberances 51,52 and 53, suitably spaced along its perimeter is mounted in the gunstructure by affixing the strap 49 to mounting posts 55, 56, 57 and 58which are embedded in glass support rods 60, 61 and 62. After theconnecting strap 49 is thus firmly mounted in the gun structure, thecenter portions of the elongated protuberances 51-53 are cut-out toprovide discontinuities in the connecting strap. The cutout of thecenter portion of the elongated protuberances can be done in anyconventional manner. For example, it can be performed manually such asby an operator using a pair of diagonal pliers or metal cutters.Furthermore, because of the close tolerances possible, the cut-outoperation could be fully automated. The ends of the heater elements 41,42 and 43 are connected to the elongated protuberances 51, 52 and 53,respectively, such that each heater element is connected across thediscontinuity in its respective elongated protuberance, thereby formingthe desired series connection of the heater elements in the gunstructure. Leads 64 and 65 affixed, respectively, to mounting posts 57and 58 are connected to the input stem leads (not shown) supplyingheater current.

The advantages of providing series heaters connections in this mannerwill be readily apparent to those skilled in the art. Since the singleconnecting strap is preformed, its dimensions can be closely controlledsuch that when placed in the gun structure, the elongated protuberancesare in positive registration with the cathode elements, therebypermitting accurate controlled placement of the heater element andsubstantially reducing the possibility of gun failure resulting from ashorted or distorted heater element. Furthermore, because the dimensionsof the connecting strap 49 are controlled, thereby assuring positiveplacement with proper registration in the gun structure,

the steps of mounting the connecting strap in the gun structure andforming the series connection are less likely to result in faults due tohuman error.

It will be appreciated that the connecting strap can be formed in avariety of shapes, depending upon particular requirements orpreferences. For example, the preformed connecting strap 79 shown inFIG. 3 is generally triangular in shape with the side of the strapconnected via mounting posts 85, 86, 87 and 88 to the glass support rods90, 91 and 92. The corners 95, 96 and 97 of the strap 79 are flattenedto provide proper registration of the strap over the cathode elementsand to facilitate the location of the cut-outs necessary to provide thediscontinuities across which the heater elements 101, 102 and 103,respectively, are connected.

As illustrated in FIG. 4, it may be desirable to cut out a portion 107in the center of the elongated protuberance 109 of the strap 110 duringthe forming operation. Then, when the strap 110 is mounted in the gunstructure, less cutting force is required to remove the remaining center111 of the elongated protuberance 109 in providing the discontinuityacross which the heater element is to be connected, and the possibilityof distorting the strap 110 during the cutting operation is reduced.

According to a further embodiment of the invention, as disclosed in FIG.5, the preformed connecting strap 115 may have one or more mounting tabs117 suitably positioned along one edge such that when placed in theelectron gun structure, the mounting tab is in registration with arespective mounting post 119 which is embedded in a glass support rod121. Utilizing this configuration, the mounting tabs will support theconnecting strap in a proper position in the electron gun structureprior to the welding operation which secures the connecting strap to themounting posts.

As shown in FIG. 6, the elongated protuberance 125 may be formed toextend inward from the circumference of the connection strap 127. Also,the connecting strap 127 may be constructed from material having asubstantially circular cross-section, i.e., wire, rather than fromribbon stock material as previously shown. The particular choice ofstrap material and strap configuration may, therefore, vary dependingupon design limitations and structural requirements without departingfrom the scope of the present invention.

Thus, there is provided improved means for interconnecting the heaterelements in a multiple electron gun structure. The utilization of thepreformed connecting strap having controlled dimensions assures theproper mounting in the gun structure in registration with the cathodeelements, thereby facilitating the correct place ment of the heaterelements within the cathode elements. Since the possibility of humanerror is substantially reduced, the resultant structure is inherentlymore reliable and less likely to fail. Also, the controlled dimensionsof the preformed connecting strap, make it possible to automate part ofthe heater element mounting process. For example, by machine process itis now possible to insert the preformed connecting strap in the electrongun subassembly, weld the strap to the mounting posts and cut out thedesired portions of the elongated protuberances prior to the insertionof the cathode heater elements, thereby providing a more economical gunstructure.

While there have been shown and described what are at present consideredthe preferred embodiments of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the scope of the invention as defined bythe appended claims.

What is claimed is:

1. A three-electrongun subassembly comprising:

three cylindrical cathode elements disposed a relatively equal distanceapart, thereby defining the corners of a triangle within saidsubassembly;

three insulating support rods each disposed adjacent one side of saidtriangle;

a preformed heater element connecting strap having two ends and havingthree elongated protuberances; and

means for securing said strap to said insulating support rods such thatthe three elongated protuberances of said strap are positioned,respectively, adjacent to said three cathode elements.

2. The invention according to claim 1, wherein the shape of saidconnecting strap is circular with the two ends of said strap adjacentto, but not touching, each other and wherein said means for securingsaid strap to said insulating support rods comprise:

first and second support members connected between the two ends of saidconnecting strap, respectively,

and a first one of said three support rods; and

third and fourth support members connected between said remaining twosupport rods, respectively, and

sides of said connecting strap adjacent thereto. 3. The inventionaccording to claim 1, wherein the shape of said connecting strap istriangular with the two ends of said strap adjacent to, but not touchingeach other, and wherein said means mounting said connecting strap tosaid support rods comprise:

first and second support members connected between the two ends of saidconnecting strap, respectively, and one of said three support rods; and

third and fourth support members connected between said two remainingsupport rods, respectively, and the sides of said connecting strapadjacent thereto.

4. The invention according to claim 1 wherein said preformed heaterelement connecting strap additionally comprises a plurality of mountingtabs suitably spaced along said strap such that each of said mountingtabs is adapted to be positioned within said subassembly adjacent to oneof said insulating support rods.

5. A multiple electron gun subassembly comprising:

a plurality of cylindrical cathode elements disposed a relatively equaldistance apart;

a preformed heater element connecting strap having two ends and aplurality of elongated protuberances;

a plurality of insulating support rods; and

means for securing said strap to said plurality of insulating supportrods such that the plurality of elongated protuberances of said strapare positioned, respectively, adjacent to said plurality of cathodeelements.

References Cited UNITED STATES PATENTS 5/1964 Brown 313-271 3/1966 Brown3l3271

